You can (since 5.8; see open, search for 'scalar'):

>perl -wMstrict -le
"my $scalar_as_file;
 ;;
 open my $fh_scalar, '>', \$scalar_as_file or die qq{opening: $!};
 printf $fh_scalar q{xxx :%#x: yyy}, 55473;
 close $fh_scalar;
 ;;
 print qq{scalar as file: '$scalar_as_file'};
"
scalar as file: 'xxx :0xd8b1: yyy'
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